VOICES OF BIRDS. 269 



dicate a cause and original motive. That some of 

 the notes of birds are as language designed to 

 convey a meaning, is obvious from the very different 

 sounds uttered by these creatures at particular 

 periods : the spring voices become changed as sum- 

 mer advances, and the requirements of the early 

 season have ceased ; the summer excitements, mo- 

 nitions, informations, are not needed in autumn, 

 and the notes conveying such intelligences are no 

 longer heard. The periodical calls of animals, 

 croaking of frogs, &c., afford the same reasons for 

 concluding that the sound of their voices by ele- 

 vation, depression, or modulation, conveys intelli- 

 gence equivalent to an uttered sentence. The 

 voices of birds seem applicable, in most instances, 

 to the immediate necessities of their condition ; 

 such as the sexual call, the invitation to unite 

 when dispersed, the moan of danger, the shriek of 

 alarm, the notice of food. But there are other 

 notes, the designs and motives of which are not so 

 obvious. One sex only is gifted with the power of 

 singing, for the purpose, as Buffon supposed, of 

 cheering his mate during the period of incubation ; 

 but this idea, gallant as it is, has such slight foun- 

 dation in probability, that it needs no confutation : 

 and after all, perhaps, we must conclude, that 

 listened to, admired, and pleasing, as the voices of 

 many birds are, either for their intrinsic melody, 

 or from association, we are uncertain what they 

 express, or the object of their song. The singing 

 of most birds seems entirely a spontaneous effusion 



